Nortel Networks Nortel 8300 and slow performance after delay

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Subject Author Date
Nortel 8300 and slow performance after delay edavid3001 09-06-07
Posted by on September 6, 2007, 12:16 pm
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We have two Nortel 8300's with split multi link trunking (I think I
said that right) between them. Servers are plugged into both Nortel's
and have either switch assisted load balancing or NFT.

There are other Nortel switches (55xx/3xxx series) which sit plugged
into both core's. These have workgroup machines as well as machines
that can only support a single NIC.

When I copy over 30GB of traffic from one machine to another on this
setup, the initial 500MB or so is very quick, but then it drops down
from around 250Mb/s to about 10Mb/s and stays that way. The server I
am copying to becomes unresponsive from a network point of view,
though the copy continues.

We have an old Cisco 6509 plugged into one of the 8300's. It appears
that if I copy through a PC->Nortel 3xxx ->Nortel 8300->6509->server
then I don't have this issue.

I am more in the role of end user in this scenario. I'm the one
having the problem. Any suggestions on what to check? I've been
working w/the network guy and we're looking at this, but nothing we've
tried has helped.

Thanks!

Edwin


Posted by Dophi on September 8, 2007, 3:37 am
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On Sep 7, 12:16 am, edavid3...@gmail.com wrote:
> We have two Nortel 8300's with split multi link trunking (I think I
> said that right) between them. Servers are plugged into both Nortel's
> and have either switch assisted load balancing or NFT.
>
> There are other Nortel switches (55xx/3xxx series) which sit plugged
> into both core's. These have workgroup machines as well as machines
> that can only support a single NIC.
>
> When I copy over 30GB of traffic from one machine to another on this
> setup, the initial 500MB or so is very quick, but then it drops down
> from around 250Mb/s to about 10Mb/s and stays that way. The server I
> am copying to becomes unresponsive from a network point of view,
> though the copy continues.
>
> We have an old Cisco 6509 plugged into one of the 8300's. It appears
> that if I copy through a PC->Nortel 3xxx ->Nortel 8300->6509->server
> then I don't have this issue.
>
> I am more in the role of end user in this scenario. I'm the one
> having the problem. Any suggestions on what to check? I've been
> working w/the network guy and we're looking at this, but nothing we've
> tried has helped.
>
> Thanks!
>
> Edwin

Hi Edwin

Do you set any filters on ERS8300 or ERS3510?
Or, you can post the topology and configuration if you don't mind.
It's too hard to know what makes this issue without log,
configuration, or topology.


Posted by on September 8, 2007, 11:37 am
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QoS and Filtering are turned off. These are overkill for our
environment. We have three VLANs, #1, #2, #48, and #52 with almost
everything on #1, a TV broadcast on #2, the split mlt on 48, and
nothing on #52 but an empty port.

We did find one of the management cards in the 8300 negotiated to 100/
half. The other 8300 is at 100/full. So we're going to fix that,
but I don't think that's the issue. there are 100k/s avg on that
interface. Nothing else has a duplex mismatch. Everything is either
1000/full or 100/full in the core -- both at the switch and at the
device.

More tests. Plugging my PC into the 6509 and copying the file to a
server on the 6509 has the same results. However, plugging together
using a cross over cable and the problem goes away.

Odd problem.



Posted by on September 11, 2007, 12:48 pm
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I believe we've narrowed the problem down to old servers. The
server's disk performance is very good up to a certain point, and then
it goes to crap. If we turn on disk write caching, it's a little
better. It's not the network, apparently.



Posted by Dophi on September 12, 2007, 11:48 pm
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On Sep 12, 12:48 am, edavid3...@gmail.com wrote:
> I believe we've narrowed the problem down to old servers. The
> server's disk performance is very good up to a certain point, and then
> it goes to crap. If we turn on disk write caching, it's a little
> better. It's not the network, apparently.

It's so weird. You didn't turn on disk caching and connect to two
different end point on 8300 or 6509.
How come you could get different test result? :S


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